Tablet of a chlorine releasing solid compound

ABSTRACT

A tablet of chlorine releasing solid compound having substantially parallel plane faces in which the surfaces of the edge between the faces is sealed by water impervious and water insoluble material, which may be a continuous band of insoluble material which adheres to the compound, may be a band comprising a flexible sheet material attached to the edges of the tablet by a water insoluble adhesive, at least one of which is water impervious, or may have one of a number of alternative constructions comprising a self-adhesive tape, a coating of paint or synthetic resin, or a coating of wax. Alternatively the continuous band may be the side of a cup-like member and the tablet is sealed within the cup-like member by water impervious insoluble sealing material.

[ 1 Dec. 24, 1974 TABLET OF A CHLORINE RELEASING SOLID COMPOUND MichaelAxton May, West Hanningfield, Gay Bower Farm, England 22 Filed: Dec. 16,1969 211 Appl. No.: 885,494

[76] Inventor:

[52] US. Cl 424/16, 21/58, 206/84, 210/62, 210/64, 252/90, 252/93,252/94,

252/187, 424/32, 424/34, 424/38, 424/149, 424/249 [51] Int. CL... B65d81/00, C02b 3/08, A0ln 11/00 [58] Field of Search 424/16, 149, 249;252/90-94,'l34, 174-176, 187; 210/62, 64;

[56] References Cited UNITED STATES PATENTS 262,745 8/1882 Crump' 252/93395,243 12/1888 Maggi 206/56 X 740,440 10/1903 Jones 252/93 805,56011/1905 Kohn A 206/.5 X

1,144,186 6/1915 Freestone 252/93 1,325,361 12/1919 Harshberger 252/931,335,488 3/1920 Davis 424/10 1,393,253 10/1921 Thompson 424/6 1,413,0644/1922 Salflsberg 206/56 X 1,782,526 11/1930 Beardsley 206/56 X2,051,665 8/1936 West 215/9 X 2,312,381 3/1943 Bickenheuser.... 424/442,341,583 2/1944 Tuve 40/134 2,517,513 8/1950 Vaernet 128/272 2,519,0458/1950 Houghton. 424/15 3,113,076 12/1963 Jacobs 424/16 X 3,279,99510/1966 Reid 424/15 3,342,674 9/1967 Kowalski 424/14 3,488,420 1/1970Keast et a1. 424/128 Primary Examiner-Shep K. Rose Attorney, Agent, orFirmirving M. Weiner [57] ABSTRACT A tablet of chlorine releasing solidcompound having substantially parallel plane faces in which the surfacesof the edge between the faces is sealed by water impervious and waterinsoluble material, which may be a continuous band of insoluble materialwhich adheres to the compound, may be a band comprising a flexible sheetmaterial attached to the edges of the tablet by a water insolubleadhesive, at least one of which is water impervious, or may have one ofa number of alternative constructions comprising a self-adhesive tape, acoating of paint or synthetic resin, or a coating of wax. Alternativelythe continuous band may be the side of a cup-like member and the tabletis sealed within the cup-like member by water impervious insolublesealing material.

6 Claims, 8 Drawing Figures PATENTEUBEE24|974 3, 856,932 sum 1 BF 2'INVENTOR MICHAEL AXTON MAY /7 3.9 TTORNEY PATENTED 3,856,932

SHEET 2 BF 2 INVEN MICHAEL AX N MAY ATTORNEY TABLET OF A CHLORINERELEASING SOLID COMPOUND The invention relates to tablets of a chlorinereleasing solid compound. These tablets are used extensively for thewater treatment and sanitisation of swimming pools. See US. Pat. No.3,342,674 for a partial listing of available species of solid compoundscapable of releasing available chlorine when contacted with water, suchas a chlorinated triazine compound, or an alkaline earth metalhypochlorite compound, and mixtures thereof. One or more tablets areplaced in the pool, and the surface of the tablet coming into contactwith the water gives off chlorine which sanitises the pool. This processcontinues over a period of time, in some cases as much as 14 days, untilthe tablet is completely dissolved.

The tablets are usually about 3 inches in diameter and approximately 1inch thick, but they have the disadvantage that the amount of chlorineprovided by the tablet varies in quantity over the period of time. Whenthe tablet is placed in the water the surface area is at a maximum andit gives off a maximum amount of chlorine, but as the tablet dissolvesit is reduced in size and as the surface area is also reduced so thequantity of chlorine given off is reduced proportionately. For instance.if the tablet dissolves completely in 14 days, and when first placed inthe water maintains one part per million of chlorine in solution in thewater, after seven days the surface area has been reduced by one-third,and the amount of chlorine given off is reduced proportionately, andmaintains only two-thirds of a part per million, and from the start tothe finish the supply of chlorine differs from day to day in adecreasing amount due to the reduction of the surface area.

The object of the present invention is to provide a tablet of the kindreferred to which overcomes this drawback and provides an even, dailysupply of chlorine to the pool from start to finish.

The invention consists in a tablet of chlorine releasing solid compoundhaving substantially parallel plane faces at least one of which faces isleft completely exposed, and said tablet being sealed around its edge bya continuous band of material which is insoluble in water.

The invention further consists in a tablet as set forth in the precedingparagraph in which the sealing material is a continuous band ofinsoluble material.

The invention still further consists in a tablet as set forth above inwhich the band is formed of a length of waterproof tape.

The invention still further consists in a tablet as set forth above inwhich the edge thereof is rendered water-resistant by a material sprayedthereon.

The accompanying drawing shows, by way of example only, one embodimentof the invention in which:

FIG. I is a perspective view of a known tablet of 3 inches diameter and1 inch thick;

FIG. 2 is a perspective view of the same known tablet as shown in FIG. 1after having been immersed in water for 7 days;

FIG. 3 shows a perspective view of a tablet constructed in accordancewith the present invention,

FIG. 4 shows a perspective view of a tablet of FIG. 3 having beenimmersed in water for seven days, while FIGS. 5, 6, 7 and 8 are crosssections of a tablet constructed in four different ways in accordancewith the invention.

The tablet shown in FIG. 1 if 3 inches in diameter and 1 inch thick hasa surface area of 23 /2 sq. in. and the quantity of chlorine released inwater is proportional to the surface area. If such a tablet is immersedin water for seven days it is reduced to the size shown in FIG. 2 inwhich it has a surface area of 14 /2 sq. in. and the release of chlorineto the water has been reduced in proportion to the surface area of thetablet, as previously mentioned.

The tablet shown in FIG. 3 is of the same size as that shown in FIG. 1,but the edge is protected by a waterproof band or seal and the surfacearea exposed to the water is 15 sq. in. After such a tablet constructedin accordance with the invention has been left in the water for sevendays the surface area still exposed to the water is the same as whenfirst inserted, namely 15 sq. in. and in the release of chlorine to thewater has remained constant over that period, and will continue to do sofor substantially the whole life of the tablet.

In FIG. 5 the tablet of chlorine releasing solid compound l is housed ina cup-like member 2 by a water impervious and insoluble sealing material3, which can conveniently be painted upon either or both the innersurfaces of this cup-like member at the edge and bottom of the tablet,and be of a rubbery nature, and the latter pressed into the former toseal both the edge and bottom against contact with the water in theswimming pool. The cup-like member may be constructed of a suitableinsoluble material such as metalor plastics, or other rigid orsemi-rigid material as required.

It is not essential that one of the faces of the tablet be sealed as inFIG. 5, and in consequence it is proposed in an alternative form ofconstruction, as shown in FIGS. 6 and 7, to cover only the edge of thetablet by an impervious and water insoluble material. In FIG. 6 there isshown a rigid band of metal, plastic or other suitable material 4, inwhich the edge of the tablet is sealed within the ring by a sealing oradhesive compound 3. When lying on a horizontal surface in the water,the lower surface being covered, dispersion of the chlorine takes placeprincipally from the exposed upper surface, and it acts in a similarmanner to the construction of FIG. 5.

In the construction of FIG. 7 the sealing of the edge by a waterimpervious and water insoluble material can be carried out in a numberof different ways. The water insoluble material 5 may be a band offlexible sheet material which is attached to the tablet by a waterinsoluble adhesive, at lest one of which is water impervious. Forexample, there may be applied to the tablet a selfadhesive tape, or theadhesive may be applied firstly to the edge of the tablet and theadhesive covered by a band, for example of aluminium foil, or viceversa.

In accordance with the construction of FIG. 7 the edge of the tablet maybe sealed by a coating of liquid, which when dry adheres to the tablet,and forms a water insoluble and impervious seal 5. The liquid may be ofa suitable paint, a synthetic resin, a natural or synthetic rubber, orit may be a coating of wax or other suitable material.

One face of the tablet may also be sealed as shown in FIG. 8 by one orother of the methods described in relation to FIG. 7, and may be thesame or different from that applied to the edge of the tablet.

The layer of waterproofing does not have to be very thick, a thin coatis sufficient so long as it is just thick enough to seal the edge of thetablet against penetration of the water radially inwards, and adheresfirmly to the granules face of the edge of the tablet during handling.The water must be prevented from obtaining access to the surface of theedge from the face of the tablet, under the sealing coating, andtherefore it is essential that the latter should adhere firmly to thesurface of the edge to prevent solution of the tablet inwardly from theedge.

If the sealing material is placed only upon the edge of the tablet, thetablets may be placed one upon another in a cylindrical form, and besprayed together. The tablets may be used in that form, two or moretogether, to provide two or more times the period before replacement isrequired, or the tablets may be broken apart for use separately,immediately after the coating has dried, or when required for use, whileother details to carry the invention into effect may be varied withoutdeparting from the scope of the invention claimed.

I claim:

1. A tablet comprised of a chlorine releasing solid chemical compoundfor use as an agent for sanitizing water, said tablet havingsubstantially parallel plane faces, the surface of the edge between saidsubstantially parallel plane faces is sealed by a continuous band of awater impervious and water insoluble waterproof material, at least oneof said substantially parallel plane faces being left completely exposedfor chlorine release when placed in said water so that the surface areaof said tablet exposed for chlorine release in said water remainsconstant for substantially the entire life of said tablet.

2. A tablet as claimed in claim 1 in which the tablet edge surfacesealing material is a continuous band of insoluble material whichadheres to the edge surface of the tablet.

3. A tablet as claimed in claim 2 in which the continuous sealing bandcomprises a flexible sheet material attached to the edge of the tabletby a water insoluble adhesive, at least one of which is waterimpervious.

4. In the art of chlorinating swimming pools by placing one or morechlorine releasing tablets in the pool whereby the contacting of thesurface of the tablet with the water in the pool gives off chlorine overa period of time, until the tablet is completely dissolved, thechlorination process improvement comprising the step of providing aneven daily supply of chlorine to the pool from start to finish byplacing in the pool a swimming chlorinating tablet comprised of achlorine releasing solid chemical compound as an essential watersanitizing agent and having substantially parallel plane facescompletely exposed for chlorine release when placed in water, thesurface of the edge between the exposed faces being sealed by acontinuous band of a water impervious and water insoluble water proofmaterial. the tablet being so constructed that the exposed surface ofthe tablet remains constant over substantially the entire life of thetablet.

5. A process as claimed in claim 4 in which the tablet edge surfacesealing material of the tablet employed is a continuous band ofinsoluble material which adheres to the edge surface of the tablet.

6. A process as claimed in claim 5 in which the continuous sealing bandof the tablet employed comprises a flexible sheet material attached tothe edge of the tablet by a water insoluble adhesive, at least one ofwhich is water impervious.

1. A TABLET COMPRISED OF A CHLORINE RELEASTING SOLID CHEMICAL COMPOUNDFOR USE AS AN AGENT FOR SANITIZING WATER, SAID TABLET HAVINGSUBSTANTIALLY PARALLEL PLANE FACES, THE SURFACE OF THE EDGE BETWEEN SAIDSUBSTANTIALLY PARALLEL PLANE FACES IS SEALED BY A CONTINUOUS BAND OF AWATER IMPERVIOUS AND WATER INSOLUBLE WATERPROOF MATERIAL, AT LEAST ONEOF SAID SUBSTANTIALLY PARALLEL PLANE FACES BEING LEFT COMPLETELY EXPOSEDFOR CHLORINE RELEASE WHEN PLACED IN SAID WATER SO THAT THE SURFACE AREAOF SAID TABLET EXPOSED FOR CHLORINE RELEASE IN SAID WATER REMAINSCONSTANT FOR SUBSTANTIALLY THE ENTIRE LIFE OF SAID TABLET.
 2. A tabletas claimed in claim 1 in which the tablet edge surface sealing materialis a continuous band of insoluble material which adheres to the edgesurface of the tablet.
 3. A tablet as claimed in claim 2 in which thecontinuous sealing band comprises a flexible sheet material attached tothe edge of the tablet by a water insoluble adhesive, at least one ofwhich is water impervious.
 4. In the art of chlorinating swimming poolsby placing one or more chlorine releasing tablets in the pool wherebythe contacting of the surface of the tablet with the water in the poolgives off chlorine over a period of time, until the tablet is completelydissolved, the chlorination process improvement comprising the step ofproviding an even daily supply of chlorine to the pool from start tofinish by placing in the pool a swimming chlorinating tablet comprisedof a chlorine releasing solid chemical compound as an essential watersanitizing agent and having substantially parallel plane facescompletely exposed for chlorine release when placed in water, thesurface of the edge between the exposed faces being sealed by acontinuous band of a water impervious and water insoluble water proofmaterial, the tablet being so constructed that the exposed surface ofthe tablet remains constant over substantially the entire life of thetablet.
 5. A process as claimed in claim 4 in which the tablet edgesurface sealing material of the tablet employed is a Continuous band ofinsoluble material which adheres to the edge surface of the tablet.
 6. Aprocess as claimed in claim 5 in which the continuous sealing band ofthe tablet employed comprises a flexible sheet material attached to theedge of the tablet by a water insoluble adhesive, at least one of whichis water impervious.